.22 Marauder - Limits of striker adjustment

[mrodnewbie]

The manual describes the striker adjustable from 0 to 12 turns from full out.  I have been seeking a tune at 10 ft lbs where my velocity screw is 4 turns (fully out).  The idea was to be able to switch from 21 ft. lbs to 10 ft. lbs only by adjusting the hammer spring, striker and fill pressure.   I found that 0-HS, 13 Str, 1600 fill pressure  gave 14.3 Premiers a peak of 570 fps at 1450 psi.   Would be totally happy with this but have begun to worry that the striker adjustment is just too far out (being beyond the recommended range). Am I running any risk of damaging my rifle at this setting?  Certainly know I need to be careful about how much I fill the rifle with these setting to prevent valve lock but I do fill my rifle with an air pump and my 21 ft.lb tune has a fill pressure of only 2200 psi (peaks at 1800).

Thank you in advance for your thoughts and opinions.

[Motorhead]

Sadly in the way a Marauder hammer is designed and regards to the Stroke adjustment ....
As the striker tip is extended forward reducing stroke, the hammer is moved reward adding more hammer spring preload.

While you can find a decent tune with application of reduced transfer size screwing in the restriction screw, running it wide open your shot string profile will be pretty wide !

If you were running a regulated set up you would have far better control of velocity and stability with stroke / transfer setting tweaks.
Unregulated the 3 adjustments of Stroke / Transfer restriction / Spring tension are used together to get the unregulated action to make shots that are most stable within a specific fill pressure range.

Sadly you won't get the results of 2 very different tunes with out some major manipulation of all 3 adjustments.

IMO ... your & others mileage may differ 

[mrodnewbie]

When I first tested the tune I didn't expect to find what you warned of but it was certainly there.  I began shooting at 1800 psi and the velocity kept rising ... and rising.  The settings substantially changed the optimum pressure which is around 1450-1460.   Also, where the 21 ft. lb. is stable over a 750 psi drop in pressure, this one provides around 240 psi drop (1600 to 1360) where the ES is less than 4%.  Not very broad, but because of efficiencies gained with the velocity screw full open it provides 40 shots (around 6 psi per shot).  Certainly, shot count with the tune isn't very high.

I've not been at it very long and yet it is clear that the rifle and valve are really intended to operate at higher pressures and energies than I am asking of it with the backyard tune.  If I restrict with the velocity screw the efficiency suffers considerably.  If I modify fill pressure, striker, and hammer string to achieve the desired energy, the velocity is stable over a smaller range of pressures.